balance TA and PH

[gmh757]

Hi all. I'm having an issue with the TA and Ph in my pool. I've been trying to keep my TA around 100 by adding baking soda. I'll put in 8-10 lbs of it, to bring the TA up to 100. It seems to last about a month, gradually dropping to 60. Then I'll throw in some more baking soda, and start the process again. I also end up adding a gallon of muriatic acid every 5-7 days. Is this excessive? Should I just let the TA stay at about 60?
Here are my current readings:
Ph 7.3
FC 5
TA 60
CH700
CYA 56
By the way, I put in 2 gallons of acid on Nov 1, which lowered the Ph from 7.9 to 6.8 (I had been out of town for over a week, and things got out of whack). My TA went from 90 to 60 after adding the acid. Checking 4 days later, my Ph rose to 7.3. This kind of movement seems excessive to me. Ideas, anyone?

 

[bdavis466]

Alkalinity is a source of rising pH in pools. A swimming pool's water is intentionally over saturated with bicarbonate (alkalinity) as a means of protecting your plaster surface from the water being too aggressive and leaching the calcium out of the plaster surface (essentially shortening its lifespan).

You are somewhat chasing your tail with baking soda and acid. Raising the TA (baking soda) causes your pH to rise quickly which means you add acid to lower your pH and in turn lower your TA as well...the cycle continues.

Being that your TA wants to settle at 60, I'd recommend leaving it there and target a pH of 7.6-7.8.Your acid additions should drop drastically and you should have no need to add any baking soda.

Please post all of your numbers from the most recent test. Without them, it is difficult to give any further advice.

 

[Texas Splash]

bdavis466 is correct. Keep your numbers in-line with the Pool School - Recommended Levels and you'll do fine. Your TA is just fine around the 70-90 range. Even 60 won't hurt anything. Always look closely in the Poolmath calculator and it will set you straight. Also, after you've loaded your numbers from each test, look at the CSI row to ensure your saturation index is within acceptable limits. When you temporarily dropped your pH to 6.8, CSI got a bit low, but with pH at 7.6-7.8 all is well. CSI is something to always watch since you are in an area with notoriously hard water. Have a nice weekend.

 

[ping]

Welcome to TFP!

How old is the plaster?

Aeration causes the pH to rise, how often does the waterfall run?

With that high of CH, you should let the TA drop to 60 which will help slow down the rising pH. There is no need to keep the TA higher and you will use far less acid if you target the pH in the 7.5/7.8 range.

 

[Divin Dave]

To add what the others have said....
pH seems to rise quicker when its on the low side. For example, it will rise from 7.2 to 7.5 quicker that it will rise from 7.6 to 7.9

I also agree to leave your TA at 60, and let it rise to 7.6ish, then see what happens.
I would also ask which type of test kit are you using? There are many out there which are notoriously inaccurate.

 

[gmh757]

Alkalinity is a source of rising pH in pools. A swimming pool's water is intentionally over saturated with bicarbonate (alkalinity) as a means of protecting your plaster surface from the water being too aggressive and leaching the calcium out of the plaster surface (essentially shortening its lifespan).

You are somewhat chasing your tail with baking soda and acid. Raising the TA (baking soda) causes your pH to rise quickly which means you add acid to lower your pH and in turn lower your TA as well...the cycle continues.

Being that your TA wants to settle at 60, I'd recommend leaving it there and target a pH of 7.6-7.8.Your acid additions should drop drastically and you should have no need to add any baking soda.

Please post all of your numbers from the most recent test. Without them, it is difficult to give any further advice.

Thanks all. I did add 10 pounds of baking soda which brought my TA to 95 and my Ph to 7.6. I'll try letting things ride for a while and see what I get. Thanks for the input!!

 

[YippeeSkippy]

As your pH rises, use the MA to lower it. That will also lower your TA, but don't then try to raise the TA. Let the TA remain lower (60-70ish) and it will help keep the pH from rising so much so fast.